2013 Chrysler 300S5.7l

Tripped this code about a month ago and took it to the dealer since I purchased the extended warranty plan. Was told the passenger side catalytic converter was not attached to the vehicle and charged me $115.00 for it. It's been a few years since I've worked on them but for the $1800.00+ they wanted for new cats I would fix it myself. The picture included was the only exhaust leak on the car, the cats were solid. I fixed the exhaust leak myself, about a week later, CEL came back on...Same code. They acknowledged the cat was "reattached" the second time and drove my car for 100 miles and "could not duplicate the problem". So here we are. Before I decide to challenge them, I just wanted to double check as maybe it's time for me to hit the books and freshen my knowledge. Basically I am just curious how an evap code being tripped would have anything to do with the leaking exhaust? Am I that far behind? I could see maybe a few other codes by a cat being "not attached to the vehicle" but a P0455?